Get yourself the liners and some nylon glove shells. The shells are light and you can carry them in your pocket. IF the liners are not warm enough on their own slip on the shells. The liners will be much warmer with the shells on them. I find that the easiest way to get a good quality lightweight shell is to buy a pair of cheap insulated ski gloves from Walmart that have a good shell on them and cut out all the liner and membranes. These are usually under 10 bucks. Ski gloves in this price range are usually touted as waterproof because they have a waterproof lining. They do but they don't breath so they are only good for one bike ride. With this approach you can use either a thin glove liner for insulation or a medium thick cheap fleece glove which will be a lot warmer than the thin glove liner. So you have four combinations for different temps.